Synthesis of 2,5‐Diformylfuran and Furan‐2,5‐Dicarboxylic Acid by Catalytic Air‐Oxidation of 5‐Hydroxymethylfurfural. Unexpectedly Selective Aerobic Oxidation of Benzyl Alcohol to Benzaldehyde with Metal=Bromide Catalysts

The alcohol group of hydroxymethylfurfural (compound 1, HMF) is preferentially oxidized by dioxygen and metal/bromide catalysts [Co/Mn/Br, Co/Mn/Zr/Br; Co/Mn=Br/(Co+Mn) = 1.0 mol/mol] to form the dialdehyde, 2,5‐diformylfuran (compound 2, DFF) in 57% isolated yield. HMF can be also oxidized, via a network of identified intermediates, to the highly insoluble 2,5‐furandicarboxylic acid (compound 5, FDA) in 60% yield. For comparison, benzyl alcohol gives benzaldehyde in 80% using the same catalyst system. Over‐oxidation (to CO₂) of HMF is much higher than that of the benzyl alcohol but can be greatly reduced by increasing catalyst concentration.     

Carbon dioxide reforming of methane over Co-X/ZrO2 catalysts (X = La,Ce, Mn,Mg, K)

Dry reforming of methane has been studied over Co/ZrO₂ catalysts promoted with different metal additives (La, Ce, Mn, Mg, K) aiming to improve the performance of the catalysts and increase their resistance to coking. Scanning electron microscopy studies and different activity levels of the catalysts clearly show that the type of the promoter significantly affected the metal dispersion properties and catalytic performances of Co/ZrO₂ catalysts. La-modified catalyst exhibited high stability, but moderate activity. It showed no severe coke deposition. Ce-doped Co/ZrO₂ displayed the highest activity among all the catalysts prepared and had a very limited activity loss.     

Oxidation of styrene over polymer‐ and nonpolymer‐anchored Cu(II) and Mn(II) complex catalysts

Catalytic oxidation of styrene was investigated over polymer‐ and nonpolymer‐anchored Cu(II) and Mn(II) complex catalysts prepared by schiff base tridentate ligands. The effect of temperature, styrene to H₂O₂ mole ratio and catalyst amount on the catalytic activity and product selectivity was investigated. Further, the catalysts were characterized by various techniques, such as elemental analysis, atomic absorption spectroscopy (AAS), FTIR, FE‐SEM, EDAX, TGA, and UV–vis spectrophotometer. The elemental analysis, EDAX and AAS results confirmed the formation of Cu(II) and Mn(II) complexes, and it was found that the metal loading in the polymer‐anchored complex catalysts were in the range of 0.53–3.74 %. FTIR results showed the co‐ordination bond formation between the polymer ligands and metal ion. The catalytic data showed that, over all the catalysts, the main reaction products were benzaldehyde, styrene oxide, and benzoic acid. The polymer‐anchored complex catalysts were found to be much more active when compared with nonpolymer‐anchored catalysts. The maximum conversion of styrene (92.3%) was obtained over PS‐[Cu(Hfsal‐aepy)Cl] catalyst with benzaldehyde selectivity to 69% at the styrene to H₂O₂ mole ratio of 1 : 4 at 75°C. Although the PS‐[Mn(Hfsal‐aepy)Cl] catalyst was less active, it was highly selective to benzaldehyde. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Effect of Divalent Metal Component (MeII) on the Catalytic Performance of MeIIFe2O4 Catalysts in the Oxidative Dehydrogenation of n-Butene to 1,3-Butadiene

A series of metal ferrite (Me^IIFe₂O₄) catalysts were prepared by a co-precipitation method with a variation of divalent metal component (Me^II = Zn, Mg, Mn, Ni, Co, and Cu) for use in the oxidative dehydrogenation of n-butene to 1,3-butadiene. Successful formation of metal ferrite catalysts with a random spinel structure was confirmed by XRD, ICP-AES, and XPS analyses. The catalytic performance of metal ferrite catalysts in the oxidative dehydrogenation of n-butene strongly depended on the identity of divalent metal component. Acid properties of metal ferrite catalysts were measured by NH₃-TPD experiments, with an aim of correlating the catalytic performance with the acid property of the catalysts. It was revealed that the yield for 1,3-butadiene increased with increasing surface acidity of the catalyst. Among the catalysts tested, ZnFe₂O₄ catalyst with the largest surface acidity showed the best catalytic performance in the oxidative dehydrogenation of n-butene.     

Study on Cu–Mn–Si catalysts for synthesis of cyclohexanone and 2-methylfuran through the coupling process

A series of Cu–Mn–Si catalysts for synthesis of cyclohexanone (CHN) and 2-methylfuran (2-MF) through the coupling of cyclohexanol (CHL) dehydrogenation and furfural (FFA) hydrogenation were prepared by co-precipitation method. The catalysts were characterized by using N₂ physisorption, X-ray diffraction (XRD), H₂ temperature programmed reduction (H₂-TPR), N₂O-chemisorption and ammonia temperature-programmed desorption (NH₃-TPD) methods. The results show that metal–silica/or metal–metal interactions are presented in the catalysts, and the contents of copper, manganese and silicon affect the BET surface area, acidity and copper dispersion. The results of the catalytic tests indicate that manganese increases the activity of CHL dehydrogenation and FFA hydrogenation as well as the selectivity of 2-MF. A Cu–Mn–Si catalyst including appropriate copper, manganese and silicon is found to be most active, selective and stable under reaction conditions.     

钴锰整体式催化剂的电沉积法制备及NO催化氧化性能

整体式催化剂性能高效、应用广泛,而制备方法是影响其性能的关键因素,因此探究简单高效的制备方法对整体式催化剂的工业应用至关重要。本研究以碳纤维布为载体,采用电沉积方法制备了一系列钴锰整体式催化剂,在固定床反应装置上考察了其催化氧化NO性能,并借助拉曼光谱仪、X射线衍射仪和扫描电镜等分析技术对催化剂进行表征。结果表明,采用电沉积法制备的钴锰二元催化剂比相同方法制备的氧化钴或氧化锰一元催化剂的粒径小,且钴锰比例对催化剂粒径影响很大,最小粒径为3～4nm。不同摩尔比例的钴锰二元催化剂焙烧之后物相差别较大,Mn/Co较高的催化剂的主要组成为Mn₃O₄,Mn/Co较低则趋向Co₃O₄,其中Mn/Co=2时,催化剂为(CoMn)(CoMn)₂O₄。电沉积法制备的钴锰整体式催化剂催化氧化NO的性能要远优于相同方法制备的氧化锰催化剂,在50℃下转化率均接近100%。     

Mesoporous molecular sieve MCM-41 supported Co–Mo catalyst for hydrodesulfurization of dibenzothiophene in distillate fuels

A mesoporous aluminosilicate molecular sieve with MCM-41 type structure was synthesized using aluminum isopropoxide as the Al source. Supported Co–Mo/MCM-41 catalysts were prepared by co-impregnation of Co(NO₃)₂·6H₂O and (NH₄)₆Mo₇O₂₄ followed by calcination and sulfidation. For comparison, conventional Al₂O₃-supported sulfided Co–Mo catalysts were also prepared using the same procedure. These two types of catalysts were examined at two different metal loading levels in hydrodesulfurization of a model fuel containing 3.5 wt% sulfur as dibenzothiophene in n-tridecane. At 350–375°C under higher H₂ pressure (6.9 MPa), sulfided Co–Mo/MCM-41 catalysts show higher hydrogenation and hydrocracking activities at both normal and high metal loading levels, whereas Co–Mo/Al₂O₃ catalysts show higher selectivity to desulfurization. Co–Mo/MCM-41 catalyst at high metal loading level is substantially more active than the Co–Mo/Al₂O₃ catalysts.     

Characteristics of Fe/AlPO4-5 catalyst prepared with organic solution

The Fe/AlPO₄-5 catalysts are prepared by impregnation with aqueous and organic solution (acetic acid, alcohol and acetone) of iron(III) nitrite respectively. The characterization of catalyst by means of XPS, Mössbauer spectroscopy, TPR and CO hydrogenation is reported. The catalyst prepared with the aqueous solution has no activity for CO hydrogenation because the Fe(III) in the catalyst cannot be reduced to -Fe. However, the catalysts prepared with organic solution possess obvious hydrogenation activity, in which -Fe is present in the initial reduced catalyst besides Fe³⁺ and Fe²⁺. The results may be explained by the interaction degrees between the metal and the support induced by the different impregnation solvents.     

Gas phase hydrogenation of ortho-chloronitrobenzene (O-CNB) to ortho-chloroaniline (O-CAN) over unpromoted and alkali metal promoted-alumina supported palladium catalysts

A series of alkali metals (Li, Na, K and Cs) promoted alumina-supported palladium catalysts were prepared by a wet impregnation method and characterized by X-ray diffraction (XRD) and CO chemisorption measurements. The samples were tested for the gas phase hydrogenation of ortho-chloronitrobenzene (O-CNB) to ortho-chloroaniline (O-CAN) in a fixed-bed micro reactor at 250 °C under normal atmospheric pressure. The promoted-Pd/Al₂O₃ catalysts show higher conversion for O-CNB and the hydrogenation activity of O-CNB per site decreases with the increasing ionic radius of the alkali metal promoter ions. However, the selectivity for O-CAN remains more or less the same in both unpromoted and promoted catalysts and also irrespective of the nature of the alkali metal promoter ions used for promotion of alumina support. Despite, similar activity and selectivity observed between Li- and Na-promoted Pd/Al₂O₃ catalysts, the Na-promoted showed higher resistance for coke formation than a Li-promoted catalyst. The increase in the intrinsic activity of palladium site on alkali promotion has been attributed to the increase in hydrogenation activity over promoted catalysts.     

Influence of the promoter's nature (nickel or cobalt) on the active phases ‘Ni(Co)MoS’ modifications during deactivation in HDS of diesel fuel

The characterization of various spent Ni(Co)MoP/Al₂O₃ catalysts has been performed in order to elucidate the active phase modifications undergone on the catalysts at operating conditions. Six catalysts coming either from industrial or pilot reactors were studied. The deactivation level (for hydrogenation reaction) can be determined by XPS analysis quantifying the ‘Ni(Co)MoS’ mixed phase amount. The spent catalyst active phases characteristics, at different levels of deactivation, firstly evidenced that the coke particularly influences the CoMo active phase (X-ray photoelectron spectroscopy) lowering the ‘CoMoS’ mixed phase amount. On the spent NiMo catalysts, most of the nickel is segregated (XPS, Extended X-ray Absorption Fine Structure, Transmission Electronic Microscopy/Energy Dispersive Spectroscopy) even after low residence time in the unit (pilot plant origin). In both cases it leads to the progressive deactivation of the catalyst. The coke does not seem to influence the ‘NiMoS’ mixed phase amount excepted at its life-end.     

Co/SiO2 catalysts prepared from Co2(CO)8 for CO hydrogenation into alcohols and hydrocarbons: characterization by magnetic methods and temperature-programmed hydrogenation

The hydrogenation of carbon monoxide over Co/SiO₂ catalysts obtained by reduction of precursors prepared by the reaction of dicobaltoctacarbonyl with silica gives rise to a mixture of alcohols and hydrocarbons. The chain growth probability for hydrocarbon synthesis is similar to that observed over conventional catalysts prepared by the ammonia method (=0.74) with a comparable metal dispersion (metal particle size 4 nm). Alcohol formation yields a smaller chain growth probability (=0.42). Magnetic measurements have shown that in the latter catalyst, small cobalt clusters (1 nm) are likely to be present together with the cobalt particles (4 nm), this observation reconciles apparently conflicting results from the literature. It has been speculated that alcohol formation might be related to the presence of these clusters according to a concerted mechanism. Furthermore, the observation of large amounts of acetates by temperature-programmed hydrogenation, not detected in hydrocarbon selective catalysts, suggests that they may play a role in ethanol synthesis.     

Selective hydrogenation of (E)-2-hexenal to (E)-2-hexen-1-ol over Co-based bimetallic catalysts

Hydrogenation of (E)-2-hexenal was carried out in a liquid phase using Co-based bimetallic catalysts (M–Co/Al₂O₃, M=Pd, Pt, Ru, Rh, Sn, Fe, or Cu). Pd–Co/Al₂O₃ showed the highest activity among the catalysts tested and catalyzed the hydrogenation of CC bond predominantly to produce hexanal and 1-hexanol. Pt–Co/Al₂O₃ was more active than monometallic Co/Al₂O₃ for the hydrogenation of CO bond. The excellent result, 92% selectivity to (E)-2-hexen-1-ol formation at 90% conversion, was obtained by the hydrogenation over Pt–Co/Al₂O₃ bimetallic catalyst. No improved activities were observed for the other bimetallic catalysts.     

金属添加剂对Ni-B非晶态合金催化剂邻氯硝基苯加氢性能的影响

研究金属添加剂（Cr、Mn、Fe、Co、Cu、Mo和Zn）负载的Ni-B非晶态合金催化剂催化加氢制备邻氯苯胺的影响。结果表明,适量的Zn、Cr和Mo能提高催化剂的活性和选择性,Mn对催化剂的活性和选择性影响不大,Fe、Co和Cu降低催化剂的活性。这与能和硝基形成多位吸附的单元镍以及电子因素有关。     

Room temperature oxidation of acetone by ozone over alumina-supported manganese and cobalt mixed oxides

Volatile organic compounds (VOCs) are among the major sources of air pollution. Catalytic ozonation is an efficient process for removing VOCs at lower reaction temperature compared to catalytic oxidation. In this study, a series of alumina supported single and mixed manganese and cobalt oxides catalysts were used for ozonation of acetone at room temperature. The influence of augmenting the single Mn and Co catalysts were investigated on the performance and structure of the catalyst. The manganese and cobalt single and mixed oxides catalysts of the formula Mn10%-CoX and Co10%-MnX (where X= 0, 2.5%, 5%, or 10%) were prepared. It was found that addition of Mn and Co at lower loading levels (2.5% or 5%) to single metal oxide catalysts enhanced the catalytic activity. The mixed oxides catalysts of (Mn10%-Co2.5%) and (Mn10%-Co5%) led to acetone conversion of about 84%. It is concluded that lower oxidation state of the secondary metal improves ozone decomposition and oxidation of acetone.     

CARBON DIOXIDE METHANATION ON ORDERED MESOPOROUS CO/KIT-6 CATALYST

Mesoporous Co/KIT-6 and Co/SiO₂ catalysts were prepared via hydrogen reduction and were subsequently used in CO₂ catalytic hydrogenation to produce methane. The properties of the prepared Co/KIT-6 catalyst were investigated by low-angle X-ray diffraction, Brunauer-Emmett-Teller analysis, and transmission electron microscopy. The results indicate that the synthesized Co/KIT-6 catalyst has mesoporous structures with well-dispersed Co species, as well as higher CO₂ catalytic hydrogenation activities than that of the Co/SiO₂ catalyst. The Co/KIT-6 catalyst has a large specific surface area (368.9 m² · g^?1) and a highly ordered bicontinuous mesoporous structure. This catalyst exhibits excellent CO₂ catalytic hydrogenation activity and methane product selectivity; the CO₂ conversion and methane selectivity of the Co/KIT-6 catalyst at 280°C are 48.9% and 100%, respectively. The highly ordered, bicontinuous mesoporous structure of the Co/KIT-6 catalyst improves selectivity for the methane product.     

Sustainable utilization of lignocellulose: Preparation of furan derivatives from carbohydrate biomass by bifunctional lignosulfonate-based catalysts

Bifunctional lignosulfonate-based catalysts (LS-M) with Lewis acid and basic sites were designed and prepared by immobilizing metal ions on lignosulfonate. Catalysts were characterized by XRD, XPS, SEM, EDX, TEM, TGA, NH₃/CO₂-TPD and FTIR, and applied in transformation of carbohydrate biomass to furan derivatives (HMF/furfural) in mixed water/THF systems. With LS-Cr as catalyst, the optimized yields of HMF from cellulose, glucose and mannose were 46.3%, 60.4% and 68.8%, and that of furfural from xylan, xylose and arabinose were 40.2%, 73.1% and 51.6%, respectively. The catalysts could be easily recycled with negligible wastage of the active metal ions.     

MgO-supported cluster catalysts with Pt–Ru interactions prepared from Pt3Ru6(CO)21(μ3-H)(μ-H)3

Bimetallic MgO-supported catalysts were prepared by adsorption of Pt₃Ru₆(CO)₂₁(μ₃-H)(μ-H)₃ on porous MgO. Characterization of the supported clusters by infrared (IR) spectroscopy showed that the adsorbed species were still in the form of metal carbonyls. The supported clusters were decarbonylated by treatment in flowing helium at 300 °C, as shown by IR and extended X-ray absorption fine structure (EXAFS) data, and the resulting supported PtRu clusters were shown by EXAFS spectroscopy to have metal frames that retained Pt–Ru bonds but were slightly restructured relative to those of the precursor; the average cluster size was almost unchanged as a result of the decarbonylation. These are among the smallest reported bimetallic clusters of group-8 metals. The decarbonylated sample catalyzed ethylene hydrogenation with an activity similar to that reported previously for γ-Al₂O₃-supported clusters prepared in nearly the same way and having nearly the same structure. Both samples were also active for n-butane hydrogenolysis, with the MgO-supported catalyst being more active than the γ-Al₂O₃-supported catalyst.     

Comparative Study on CO2 Hydrogenation to Higher Hydrocarbons over Fe-Based Bimetallic Catalysts

This paper reports on notable promotion of C₂ ⁺ hydrocarbons formation from CO₂ hydrogenation induced by combining Fe and a small amount of selected transition metals. Al₂O₃-supported bimetallic Fe–M (M = Co, Ni, Cu, Pd) catalysts as well as the corresponding monometallic catalysts were prepared, and examined for CO₂ hydrogenation at 573 K and 1.1 MPa. Among the monometallic catalysts, C₂ ⁺ hydrocarbons were obtained only with Fe catalyst, while Co and Ni catalysts yielded higher CH₄ selectively than other catalysts. The combination of Fe and Cu or Pd led to significant bimetallic promotion of C₂ ⁺ hydrocarbons formation from CO₂ hydrogenation, in addition to Fe–Co formulation discovered in our previous work. CO₂ conversion on Ni catalyst nearly reached equilibrium for CO₂ methanation which makes this catalyst suitable for making synthetic natural gas. Fe–Ni bimetallic catalyst was also capable of catalyzing CO₂ hydrogenation to C₂ ⁺ hydrocarbons, but with much lower Ni/(Ni+Fe) atomic ratio compared to other bimetallic catalysts. The addition of a small amount of K to these bimetallic catalysts further enhanced CO₂ hydrogenation activity to C₂ ⁺ hydrocarbons. K-promoted Fe–Co and Fe–Cu catalysts showed better performance for synthesizing C₂ ⁺ hydrocarbons than Fe/K/Al₂O₃ catalyst which has been known as a promising catalyst so far.     

Stable carbon dioxide reforming of methane over modified Ni/Al2O3 catalysts

CO₂ reforming of methane was studied over modified Ni/Al₂O₃ catalysts. The metal modifiers were Co, Cu, Zr, Mn, Mo, Ti, Ag and Sn. Relative to unmodified Ni/Al₂O₃, catalysts modified with Co, Cu and Zr showed slightly improved activity, while other promoters reduced the activity of CO₂ reforming. Mn-promoted catalyst showed a remarkable reduction in coke deposition, while entailing only a small reduction in catalytic activity compared to unmodified catalyst. The catalysts prepared at high calcination temperatures showed higher activity than those prepared at low calcination temperature. The Mn-promoted catalyst showed very low coke deposition even in the absence of diluent gas and the activity changed only slightly during 100 h operation. This revised version was published online in July 2006 with corrections to the Cover Date.     

Precious-Metal-Decorated Chromium(IV) Oxide Nanowires as Efficient Catalysts for 2,4-Toluenediamine Synthesis

The catalytic hydrogenation of 2,4-dinitrotoluene (DNT) to 2,4-toluenediamine (TDA) is a key step in the production of polyurethanes; therefore, the development of efficient hydrogenation catalysts for industrial use is of paramount importance. In the present study, chromium(IV) oxide nanowires were decorated by palladium and platinum nanoparticles in a one-step, simple, and fast preparation method to yield highly efficient hydrogenation catalysts for immediate use. The nanoparticles were deposited onto the surface of CrO₂ nanowires by using ultrasonic cavitation and ethanol as a reduction agent. Beneficially, the catalyst became catalytically active right at the end of the preparation and no further treatment was necessary. The activity of the Pd- and Pt-decorated CrO₂ catalysts were compared in the hydrogenation of 2,4-dinitrotoluene (DNT). Both catalysts have shown high activity in the hydrogenation tests. The DNT conversion exceeded 98% in both cases, whereas the 2,4-toluenediamine (TDA) yields were 99.7 n/n% and 98.8 n/n%, with the Pd/CrO₂ and Pt/CrO₂, respectively, at 333 K and 20 bar H₂ pressure. In the case of the Pt/CrO₂ catalyst, 304.08 mol of TDA formed with 1 mol Pt after 1 h hydrogenation. Activation energies were also calculated to be approximately 24 kJ∙mol⁻¹. Besides their immediate applicability, our catalysts were well dispersible in the reaction medium (methanolic solution of DNT). Moreover, because of their magnetic behavior, the catalysts were easy to handle and remove from the reaction media by using a magnetic field.